With known processes and apparatus for filling and heat sealing a container, a relatively large volume of air remains in the container following its filling and heat sealing. If the container is a sack, bag or pouch (hereinafter "pouch") containing a liquid infusion, a pressure infusion cannot be performed although it would be desirable in emergencies. As a result of the pressure built up resulting from the pressure infusion, the air contained in the conventional pouch could be injected into the blood. This remaining volume of air is relatively large so that the contents level will be located at a sufficiently great distance from the heat sealing point at which the filling connection is attached.
The known process disclosed in German Patent No. A-19 31 710 is concerned with this disadvantage. Following the filling of the liquid contents into the container, the flowthrough passage of the filling connection is reduced in a first heat sealing operation. Air or some other gas is then pressed into the container producing an excess pressure. Subsequently, the filling connection is closed in a second heat sealing operation. The volume of air or gas contained in the container is also increased in this system.